Non-Contact and Real-Time Measurement of Kolsky Bar with Temporal Speckle Interferometry

Shanwei Yang,Haihui Ruan,Xiang Sun,Xu Wang,Chenjia Gao,Xin Wen,Zhan Gao

doi:10.3390/app8050808

Shanwei Yang, Haihui Ruan + Show 5 more

Open Access

https://doi.org/10.3390/app8050808

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Abstract

In this paper, a new non-contact and real-time measurement system for Kolsky bars is presented. This system uses two sets of temporal speckle interferometry in-plane displacement measurement devices to replace two strain gauges of conventional Kolsky bars. The in-plane displacement measurement of the Kolsky bar is mainly intended to provide a new test method for the dynamic mechanical properties of small-size material samples with diameters below 2 mm. This method is non-contact, does not require any intermediate medium, and can make the Kolsky bar applicable to characterizing the dynamic mechanical properties of materials under higher strain rates and smaller size conditions. The measuring devices and principles are described. In addition, a preliminary experiment is carried out to demonstrate the performance of this new device.

Highlights

In the fields of aviation, aerospace, packaging, transportation, and other areas of military and civil engineering, the materials used will encounter stress events such as explosions, rapid collision, and other impact load
The Kolsky bar based on in-plane displacement measurement is mainly intended to provide a new test method for the dynamic mechanical properties of small-size material samples
As can be seen above, the results of these verifications experiment prove that the measurement system has a very good in-plane displacement measurement capability, and the algorithm we developed can accurately calculate the information of displacement and velocity

Summary

Introduction

In the fields of aviation, aerospace, packaging, transportation, and other areas of military and civil engineering, the materials used will encounter stress events such as explosions, rapid collision, and other impact load. It is of great practical significance to study the dynamic mechanical properties of materials under high strain rate conditions for engineering design and application. The typical Kolsky bar is using two strain gages that past on the incident bar and transmitter bar to measure the dynamic mechanical properties of a material under high strain rate conditions. This method requires good adhesion between the bar and the strain gauge. The support of real-time and high-accuracy dynamic mechanical properties of materials under high strain rate conditions is required with the rapid development of industry, especially for the machinery defense industries. Traditional strain-gauge measurements of the longitudinal waves within the bars become impractical at these sizes, because the strain gauge and the bar cannot be reliably connected when the diameter of the bar is less than 3 mm [2]

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